The present invention relates generally to the production of hydrogen from fuel and more particularly to primary reactors and methods for reforming hydrocarbons.
Many fuel cell systems use a fuel processing system to break down the molecules of a primary fuel to produce a hydrogen-rich gas stream capable of powering the fuel cells. The fuel processing systems generally have a primary reactor or reformer in which hydrocarbons are initially broken down into various product gases including hydrogen.
In one type of reactor a steam reforming reaction is carried out by reacting a hydrocarbon fuel at high temperatures in the presence of steam on a suitable catalysts to give hydrogen, carbon monoxide, and carbon dioxide. The reaction is highly endothermic. In another type of reactor a partial oxidation reaction is carried out by reacting a hydrocarbon fuel in the presence of oxygen on a catalyst to produce carbon monoxide and hydrogen. The partial oxidation reaction is exothermic. Another possibility for reforming hydrocarbons is an autothermal reformer that combines catalytic partial oxidation and steam reforming wherein exothermic partial oxidation supplies the heat of reaction required for endothermic steam reforming.
Autothermal reactors are particularly suitable for use in small scale, highly integrated fuel cell systems because fewer external components, such as heat sources or heat sinks, are required. However, the need still exists for reactors that more efficiently produce hydrogen and that may be used in a variety of fuel cell systems including small scale, highly integrated fuel cell systems.